Reenforced concrete slab and core therefor



Feb. 16, 1937. A. M. BOWMAN E -r AL 2,070,577

REENFOECED CONCRETE SLAB AND COR EEEEEEE OR 19.... Wl E umlmlmuululmwmmnuu Patented F eb. 16, 1937 UNITED STATES PATENT OFFICE Arthur M. Bowman and James Lowman, Pittsburgh, Pa.; said Arthur M. Bowmanrassignor to Said James I. Bowman Application March'15, 1932, Serial No. 598,913

12 Claims.

Our invention relates to a poured'reenforced concrete slab construction and to an impro-ved form of hollow sheet metal core adapted to be incorporated in such construction.

It has been proposed heretofore to lighten poured reenforced iioors by placing hollow cores of tile or sheet metal upon forms, before pouring the concrete thereon. All types of such cores with which We are familiar, however, are characterized by numerous objections. 'Iile cores are costly, fragile and heavy, and require considerable labor to place them in position. Sheet metal cores as heretofore constructed (as shown in the Walker Patent No. 1,101,767) have been made in short sections of a number of pieces which require bolting together, and each core was supported from the form by individual means independent of all the other cores.

'I'he supports for the cores were nailed to the V`forms and when the latter were removed after setting of the concrete, the nails protruded from the lower surface of the iloor and the feet of the supports were exposed, marring the appearance of the ceiling. It was necessary to plaster the lower surface of such floor after rst clipping the protruding nails, in order to provide a satisfactory surface therefor. The shape of the cylindrical cores, furthermore, did not distribute the concrete section to the best advantage.

It is an object of our invention therefore to improve upon known types of hollow cores for use in the construction of poured reenforced concrete slabs and particularly to provide oors which have a continuous lower concrete surface in one plane.

In accordance with our invention, we form hollow cores of corrugated sheet metal. Each core comprises a body portion and a separate removable cover. The body portion may have a flat ibottorn, vertical sides, and inclined walls connecting the bottom and sides, or the flat bottom may be omitted and the inclined walls exclusively constitute the bottom of the core. The cover is substantially flat with depending flanges for tting over the vertical sides of the body portion of the core. The cores are supported above the forms by preformed wire chairs which may readily be secured thereto and also serve the purpose of securing the body portion and cover rigidly together preventing distortion of the core during the' construction operations. The chairs have rounded feet so that the concrete when poured flows around under the feet and forms a uniform unmarked lower surface for the door since the chair feet have substantially only point contact with the form. A liner within the form aids in the production of a smooth lower surface for the door. The cores are spaced one from the other by stirrup rods extending over a plurality of cores and having depending portions lying between ad- 5 jacent cores. 'Ihe depending portions of the stirrup rods also serve to support reenforcing bars between the cores.

When the cores, stirrup rods and reenforcing bars have been placed in position, the result is l a fabric or mat of metal members for receiving the concrete. The weight of the bars and rods in the mat prevents floating of the cores and the entire metal fabric is a unitary whole.

For a complete understanding o-f the invention, l reference is made to the accompanying drawing illustrating the present preferred embodiments. In the drawing:

Figure l is a side elevation of a core made according to our invention having supporting chairs associated therewith;

Figure 2 is an end view of the core as shown in Figure 1;

Figure 3 is a partial perspective view of the cover; y

Figure 4 is a similar view of the body portion;

Figure 5 is a transverse sectional view taken through a floor in which our cores are incorporated;

Figure 6 is an elevation of a modied form of chair;

Figure '7 illustrates a partial modification of the preferred form of chair; and

Figure 8 is a perspective view of an end stop for the core. 35

Referring in detail to the drawing, we form a core I0 having a body portion II and a cover I2 of corrugated sheet metal. The core may be made in anyr length, but we prefer some standard length such as eight feet, for example.

The body portion and cover of the cores may be readily assembled or separated since they are designed for a relatively loose t. As will be apparent from the drawing, the body portion II comprises a bottom I3, vertical side walls I4, and inclined portions I5 connecting the side walls to the bottom. Both the covers and the body portions of the cores may be bent to the desired shape readily in a break after corrugation. Both the covers and the body portion nest compactly 50 for shipment. Y

The body portion II, instead of having a flat bottom I3, may be composed exclusively of Vthe sides i4 and inclined portions I5 which extend to a common junction forming a V-shaped bot- V tom for theV body portion. The Walker patent above referred to shows a modified form of'core having a V-shaped bottom of the charactermen- Vtioned. This shape of core may be desirable in some `instances and is characterized by all the Vadvantages of the shape of core shown in thedrawing y Y When'the nested covers and body portions of the 'cores have been delivered on the job, they may be assembled quickly by placing the coversv on the body portions. Preformed wire chairs 1 6 Y. provide means for supporting the cores a short distance above the plane of a formrindicated at l1', which determines the lower surface of Vthe ioor; that is, the ceiling of the room-below. 5

The chairs are preferablyshaped'as'shown in Figure 2, to conform tothe shape of the cores and provide feet I8 forresting` on a 4form I'L A tie wire .I9 may be bent around the upstandingV ends 2E of the chairsY IB and said ends bent 'over as shown in -Figure 2,. The*chairs-are, therebyy secured firmly to, the cores, Y,and the covers and bodyqportions of the 'cores are likewise-secured n' to ea-ch other.v ,Insteadpflhaving both ends of the chair I6 extending vertically'when appliedto vthegcorefone endv maybe bent over as at during manufacture.v This eliminates one bending operation performed on the job.

When installing the assembled cores prepara- 'toryrto pouring, we prefer to employ stirrup rods 2| forspacing the cores from each other. The assembled cores and chairs are placed on the form jll, which may have a liner 22, in approximately the relative positions they are to occupy in the finished floor. The stirrup rods are then placed over the cores for properly spacing andaligningjthe latterin their final position.

' Slight` shifting Vof the cores relative toeach other may` be necessary'rforthis operation. As will be apparent in Figure vv5', the stirrup rod is constituted by a plurality of downwardly'extending U,shaped portions 23, connected by straightV portions 23. .The straight portions 23 are designed to rest on'the cores and the U-shaped portions .to hang therebetween.

Reenforcing bars 24 are laid` on the, U-shaped portions 23 of the stirrup rods andthe concrete mayl then be poured over thecores; stirrup'rods and reenforcing bars. As

before stated, the reenforcing bars, thestirrup rods and the cores form a unitary mat, resting .on the form, to be embedded in the concrete.

Floating of the cores is prevented by the weight of the bars and rods. A By vibrating the mat with a power hammer, the concrete ows entirely varound'the cores and chairs to form a'oor having a continuous, uniform, plane lower surface without any projections or blemishes. When the form'hasbeen removed, a finished surface is found on the bottom of the floor slab which Yrequires no further treatment to constitute a highly Y satisfactory ceiling except painting. The sur-` y face may be painted without any difficulty and the result is a smooth, finished ceiling.

VFigure 6 illustrates a chair 25 which is of onepiece construction. One end of thechair has a preformed eye 26. The other end is adapted to receive lthe eye-26 and to be bent downward as at 2T. tobind the cover `and body portionsof the core together and to ,secure the chair thereto.V

'-fThe feetof the chair 25,V instead of being bent at acute angles as in the chair i6, extend hori- Zontally as shown at a'.' Between the feet 25a is positioned Van upwardlyV extending portion 2601 .for engagement Ywith thebottom I3 of the core.

TxtThe feet125a provide agreater lengthof con- 2,ovo,577

tact with the form liner` 2'2 than do thefeetla of the chair I6, and thus avoid denting the liner when a heavy load is placed on the core assembly,

as for example, by a workman steppingV thereon.

Figure 7 illustrates a preformed tie .rod 28 having eyes 29 at either end thereof which may be substitutedY for the wire tie rod I9 with twistedV ends, shown in Figure 2. If the tie rod 28 is employed, it ris merely dropped onY the core so that the endsZll of chair I6 enter the eyes 29 ofY the-rod. The ends 20-are Vthen bent over as lbefore described.V If one end ofthe chair I6 is bent downrin the manufacture, one eyeV of the eye rod must, of course, be slipped over the bent end and the entire rod then swungdownwardlyso Vvthat the remaining `veye engages the straight end of the chair whichisfthen bent over. f

f Figure Birgillustrates a simpleform of stop for the endsV ofthe cores. to extend the cores into abutment with the supporting beams,ownofconcreteinto the open ends of the cores :may,beprevented'byjthe use rof, a stop such as that shown at 30. 'I'he stop 30 In case it is not desired comprises a flat plate ,of-appropriate' thickness engage the top of the cover Yand the tongue 33 `the lower surface thereof.

A light blow with a hammer is sufficient to secure the stop,V plates frictionally to the cores to prevent the flow of concrete thereinto. Y

The construction hereink described is characterized by many advantages over the practicefheretofore followed. By Vcross corrugating the body portions and covers of the cores, greatrrigidity is imparted to the assembled Vunit. .At the same time, the cores are light vin* weight and are rela-- tively inexpensive. They may be made from Y sheet mill scrapA The savings inconcrete ef,-

fected by the` use of the cores sometimes -run as cost of floor construction. Y.The use of cores lightens the floor and permits the use of lighter Weight supporting steel. The Yspecific shape of the cores of our invention also gives rise tothe further advantage that the section ofv concrete V high as with a substantial reduction in theV is distributed to the greatest advantage. By using a liner in the form, the lower or ceiling surface of the Vfloor is: very smooth and may be painted without plastering. The appearance of the lower surface, furthermore, is not marredbyl y f any projecting nails or chair feetexposed therein. f The chairs support the cores-at the proper di's-V tance above theV lower surface Iof the lfloor and.

the stirrup rods properly kposition the reenforcing bars. Y Thel assembly ofcoresgchai'rs, stirrup rods. Y and reenforcingV bars constitutes a unitary fabric` over which concrete( is poured( The Aunityof the fabric is such that the application of a vibrating;

hammer to one portion thereofaffectsthe vibration of the entire surrounding structure .to settle the concrete therearoundfand the weight of the'A mat or fabric prevents flotation-of thecores.-

The shape of the cores is such that concrete flows around` them with little or noobs'truction and a' smooth, plane, Ylower or ceiling surface is produced.

Many'other practical advantages of the invern-V' tionwill be apparent. No nuts, screws, bolts or` nails are necessary. A short length of small bore pipe is the only tool that is necessary for bending the upwardly extending ends of the chairs over to secure the covers on the body portions. The shape of the chair and the fact that it is drawn tightly around the core prevents distortion of the core and the shape and corrugation of the cores is a. further safeguard against this defect. The chairs are relatively inexpensive to manufacture and provide substantial support for the cores as well as protection against distortion. The simplicity of the operations necessary to assemble and place the cores reduces the labor cost and renders the system highly practical for eld use.

While the invention has been described as applied to floors cast in situ, it is equally well adapted to the manufacture of pre-cast slabs for general use, whether as floors, side-walls, bulkheads or the like.

Although we have described and illustrated herein a preferred embodiment of the invention, together with certain possible modifications thereof, it will be obvious that many changes in the described embodiment may be made without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. A core for reenforced concrete slabs, comprising a body portion having a bottom, side walls, and inclined walls connecting said bottom and side walls, a removable cover for said core, and means surrounding said core for supporting it and securing the cover and body portion together.

2. A core for concrete construction, comprising an open top channel, a substantially flat removable cover therefor, and means embracing said channel and cover for securing them together and supporting the core.

3. In a core for concrete slab construction, the combination with an open top channel having a removable cover, of a preformed wire chair for supporting said core, and a tie wire engaging said chair for securing the cover on the core.

4. A wire chair for supporting a core having a iiat bottom, inclined and vertical Walls, said chair comprising portions bent inwardly to engage the bottom and said inclined walls, and outwardly bent portions forming supporting feet.

5. A wire chair for supporting a core having a ilat bottom, inclined bottom and vertical side walls, said chair comprising portions bent inwardly to engage the bottom and said inclined walls,

and outwardly bent, substantially horizontally extending portions forming supporting feet.

6. A core for reenforced concrete construction, comprising a body portion having substantially vertical sides and a bottom including inclined walls, and a removable cover adapted to be placed on said body portion, and a wire chair for securing the cover and body together and supporting the assembled parts.

7. In a concrete slab construction, the combination with a hollow, channel-shaped core having a removable, substantially flat top, of a preformed wire chair for bracing said core against distortion and supporting it above a form.

8. In a reenforced concrete slab construction, a core having a substantially flat top, substantially vertical walls and a substantially V-shaped bottom, means for supporting the core above the bottom of the slab prior to pouring concrete, and a monolithic layer of concrete extending above and below the core and having smooth top and bottom surfaces.

9. A core for concrete construction, comprising an open top channel and a substantially iiat, removable cover therefor, and means for securing said parts together, said means having projections constituting supporting feet for the assembled core.

10. In a concrete slab construction, the combination with a hollow, channel-shaped core having a removable,v substantially i'lat top, of means embracing the core for reenforcing it against distortion, said means having feet for supporting the core above a form deck.

11. A chair, for supporting a core having inclined bottom walls, substantially vertical side walls, and a top, said chair comprising a rod having outwardly bent portions forming supporting feet, re-entrant portions adapted to engage said inclined bottom walls and substantially straight portions adapted to engage said vertical sides and extend over said top.

12. In a floor in course of construction, a form and a mat thereon comprising a plurality of substantially nat-topped cores having tapering bottoms, spacing rods resting on the cores and reenforcing bars suspended on the rods, and means for supporting said mat above the form on feet rounded to receive concrete substantially entirely thereunder. ,Y l

ARTHUR M. BOWMAN. JAMES I. BOWMAN. 

